From patchwork Mon Feb 26 03:57:53 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13571267 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CDFC11B7E3; Mon, 26 Feb 2024 03:57:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708919878; cv=none; b=hwPaNzACZTnd663q+jIbZepmjRA6osRIcMKBzv9EoTisp4iNqaxOS7WX9uF/kwXj+9BLpJSVpmnpJ3wPnmAnN4ZMVqDvNwyxdwwLvW532xhlTz/IRLu02CGWCDt/mwpQeZcdPnljPF1vi1WSVk9OCqR94He3+2W5KZyTbvAK6FI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708919878; c=relaxed/simple; bh=6eV/0foyMhUCesPp4RUIfzVdUPTf/g2H7EDQ8aK/UiE=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=WHD+RRuwZzg3rZMfFmW32rFkeio2pZE1Bw0Q2oKNoRedek0NLP0vl1/wCjQJSqfaIszNaf2GfeFzrPC3h9CI036ZvLSjlZaLEEcLHlYBa04FXhRzb6TZ5K/r9U69fXv9nXsKWqRngOFIZ5+LbUZDJihBU8THUd4g6MgYZBjEh7Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ynq5945f; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ynq5945f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FD4FC433C7; Mon, 26 Feb 2024 03:57:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708919878; bh=6eV/0foyMhUCesPp4RUIfzVdUPTf/g2H7EDQ8aK/UiE=; h=From:To:Cc:Subject:Date:From; b=Ynq5945f9Uj1pO+1l/G/qFbWR1EvKH6IbKRxedbgP32P/t1GzHI7ghH1y7slQ3xri 6u+7NYV8bF9RqPNxErTFQoXS6IjcJO4iMBFfRUolghRQoxcC19OE1RZsMni1JzlhDP K7B4smpOv8wJSbsiorRH60apN3rck2o+KFH9CsckA8lg9S9oAh25q1n886AqSztetP IP+yssUSnoS/E2mC+NBGgirFBBaATSxCsOa+qoK/gqBfBFZ+lHP9u8MLSB5hMmaxlX kY0ByORlK6EY3tV4anD8fDiXE/w2SJyEXmxvcE1XOMpAIJzjAA6R4wmZexuLfduvtu /j4kysTdW2NNg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Jiri Olsa Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mhiramat@kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v2 0/7] tracing/probes: Support function parameter access from return probe Date: Mon, 26 Feb 2024 12:57:53 +0900 Message-Id: <170891987362.609861.6767830614537418260.stgit@devnote2> X-Mailer: git-send-email 2.34.1 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi, Here is version 2 series of patches to support accessing function entry data from function *return* probes (including kretprobe and fprobe-exit event). In this version, I added another cleanup [4/7], updated README[5/7], added testcases[6/7] and updated document[7/7]. This allows us to access the results of some functions, which returns the error code and its results are passed via function parameter, such as an structure-initialization function. For example, vfs_open() will link the file structure to the inode and update mode. Thus we can trace that changes. # echo 'f vfs_open mode=file->f_mode:x32 inode=file->f_inode:x64' >> dynamic_events # echo 'f vfs_open%return mode=file->f_mode:x32 inode=file->f_inode:x64' >> dynamic_events # echo 1 > events/fprobes/enable # cat trace sh-131 [006] ...1. 1945.714346: vfs_open__entry: (vfs_open+0x4/0x40) mode=0x2 inode=0x0 sh-131 [006] ...1. 1945.714358: vfs_open__exit: (do_open+0x274/0x3d0 <- vfs_open) mode=0x4d801e inode=0xffff888008470168 cat-143 [007] ...1. 1945.717949: vfs_open__entry: (vfs_open+0x4/0x40) mode=0x1 inode=0x0 cat-143 [007] ...1. 1945.717956: vfs_open__exit: (do_open+0x274/0x3d0 <- vfs_open) mode=0x4a801d inode=0xffff888005f78d28 cat-143 [007] ...1. 1945.720616: vfs_open__entry: (vfs_open+0x4/0x40) mode=0x1 inode=0x0 cat-143 [007] ...1. 1945.728263: vfs_open__exit: (do_open+0x274/0x3d0 <- vfs_open) mode=0xa800d inode=0xffff888004ada8d8 So as you can see those fields are initialized at exit. This series is based on v6.8-rc5 kernel or you can checkout from https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/log/?h=topic/entry-data Thank you, --- Masami Hiramatsu (Google) (7): tracing/fprobe-event: cleanup: Fix a wrong comment in fprobe event tracing/probes: Cleanup probe argument parser tracing/probes: cleanup: Set trace_probe::nr_args at trace_probe_init tracing: Remove redundant #else block for BTF args from README tracing/probes: Support $argN in return probe (kprobe and fprobe) selftests/ftrace: Add test cases for entry args at function exit Documentation: tracing: Add entry argument access at function exit Documentation/trace/fprobetrace.rst | 7 Documentation/trace/kprobetrace.rst | 7 kernel/trace/trace.c | 5 kernel/trace/trace_eprobe.c | 8 kernel/trace/trace_fprobe.c | 59 ++- kernel/trace/trace_kprobe.c | 58 ++- kernel/trace/trace_probe.c | 417 ++++++++++++++------ kernel/trace/trace_probe.h | 30 + kernel/trace/trace_probe_tmpl.h | 10 kernel/trace/trace_uprobe.c | 14 - .../ftrace/test.d/dynevent/fprobe_entry_arg.tc | 18 + .../ftrace/test.d/kprobe/kretprobe_entry_arg.tc | 18 + 12 files changed, 483 insertions(+), 168 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/fprobe_entry_arg.tc create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kretprobe_entry_arg.tc -- Masami Hiramatsu (Google)